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MongoKeyValue

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Overview

This node provides a simple key-value store interface backed by a MongoDB collection. It allows users to either retrieve (get) or store (set) values associated with keys in a MongoDB database. This is useful for scenarios where you want to persist small pieces of data between workflow executions, such as caching results, storing configuration parameters, or sharing state across different parts of an automation.

Practical examples:

  • Caching API responses to reduce redundant calls.
  • Storing user preferences or tokens securely.
  • Maintaining counters or flags that influence workflow logic.

Properties

Name Meaning
Action Choose the operation: Get to retrieve a value by key, or Set to store/update a value for a key.
Key Name or ID Select an existing key from the list or specify a new key name using an expression.
New Key Name When setting a value, specify the new key name to create or update.
Value The JSON value to store when performing the Set action.
Default Value The JSON value to return if the specified key does not exist when performing the Get action.

Output

The node outputs a JSON object with a single field result containing the value associated with the specified key.

  • For the Get action:

    • If the key exists, result contains the stored value.
    • If the key does not exist, result contains the provided default value (if any).

  • For the Set action:

    • result contains the value that was stored.

No binary data output is produced by this node.

Example output JSON for a Get action:

{
  "result": {
    "someKeyData": "value"
  }
}

Dependencies

  • Requires access to a MongoDB database.
  • Needs credentials providing a valid MongoDB connection string.
  • The node interacts with a specific MongoDB database named n8n-kv and collection kv-store.
  • Proper permissions to read and write documents in the kv-store collection are necessary.

Troubleshooting

  • Connection errors: Ensure the MongoDB connection string credential is correctly configured and the database is accessible from the n8n environment.
  • Missing keys on Get: If a key does not exist, the node returns the specified default value. If no default is set, the result will be empty or null.
  • Invalid JSON input for Value or Default Value: Make sure the JSON entered in these fields is well-formed; otherwise, the node may throw parsing errors.
  • Permission issues: Verify that the MongoDB user has read/write access to the n8n-kv.kv-store collection.
  • Empty key names: Setting or getting with an empty key may lead to unexpected behavior; always provide a valid key.

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